Historically, treatment and, therefore, compliance activities associated with wastewater treatment facilities have focused on conventional pollutants. Whereas this approach has enhanced the protection of water quality, it has not intensively addressed the problems of toxic pollutants. The Water Quality Program in North Carolina has redirected and increased activities addressing the issue of toxic discharges.

Biological approaches that include ecological studies and aquatic toxicological evaluations have proven to be useful tools in the determination of impacts to aquatic ecosystems. These approaches applied concurrently with analytical determinations have resulted in a more effective compliance program and have received substantial support from administrative officials, regulators, industry, and municipalities.